The present invention relates to a method of removing palladium.
Palladium complexes having a phosphorous-type ligand (e.g. triphenylphosphine) have been used as catalysts for a variety of organic synthetic reactions such as the Suzuki coupling reaction, the Sonogashira coupling reaction, the Heck reaction, the Buchwald reaction, and the carbonylation reaction (e.g., see Ei-ichi Negishi ed. “Handbook of Organopalladium Chemistry for Organic Synthesis,” J, A John Wiley & Sons, 2002; Jiroh Tsuji, “Palladium Reagents and Catalysts-Innovations in Organic Synthesis,” A John Wiley & Sons, 1995; and The Chemical Society of Japan ed. “Jikken Kagaku Koza (Vol. 25) Yuki Gosei VII,” 4th ed. pp. 396–427, Maruzen Co., Ltd.), and these reactions are becoming more important in the production of pharmaceuticals, agricultural chemicals, electronic materials and their production intermediates. The reaction mixture after completion of the reaction, or the reaction products obtained form the reactions contain employed palladium, as an undesirable impurity, in terms of the application of the obtained chemicals. As such, for removal of palladium there have been employed various treatments such as the one using activated carbon (e.g., see Organic Process Research & Development, 2001, 5, 383), or extraction treatment with an aqueous lactic acid solution (e.g., see J. Org. Chem., 2003, 68, 2633).
According to the present invention, efficient removal of palladium in a solution can be accomplished.
An aspect of the present invention relates to
a method for removing palladium, which method comprises contacting a solution containing a palladium complex comprising a phosphorus-type ligand in an organic solvent with a layered clay compound or a zeolite having a pore diameter of 0.6 to 2 nm.